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Back in November, Bill Gates visited a plant that turns poop into water, and he took a nice big gulp.

The machine is called an Omniprocessor, and it uses a steam engine to convert raw sewage into electricity, clean drinking water and ash. On top of that, it produces enough excess energy to power itself.

He wrote about the experience on his blog:

"I watched the piles of feces go up the conveyer belt and drop into a large bin. They made their way through the machine, getting boiled and treated. A few minutes later I took a long taste of the end result: a glass of delicious drinking water."

The visit was part of The Gates Foundation's efforts to improve sanitation in poor countries. A few years ago, he asked people to try to reinvent the toilet as a possible solution to the problem.

The Omniprocessor was built by the Seattle-based Janicki Bioenergy, which will be conducting a pilot test of the machine in Dakar, Senegal in late 2015.

So how did the water taste?

"The water tasted as good as any I've had out of a bottle," Gates writes. "And having studied the engineering behind it, I would happily drink it every day. It's that safe."